Magnetic storage system



May 21, 1963 G. G. HOBERG ETAL MAGNETIC STORAGE SYSTEM Original FiledOct. 16, 1956 2 Sheets-Sheet 1 S GR m BC N O F. E H N V .H m Go EH G mmmm wz; um 555.232 W mOFOmJmw IOmPZOU ATTO N Y May 21, 1963 G. G. HQBERGETAL 3,090,947

MAGNETIC STORAGE SYSTEM Original Filed Oct. 16, 1956 2 Sheets-Sheet 2STATOR f -M- Fl'g. 5 INVENToRs GEORGE G. HOBERG BY OTTO HOHNECKER lATTOKY United States Patent O 3,096,947 MAGNETIC STORAGE SYSTEM GeorgeG. Hoberg, Berwyn, Pa., and Y(ltto Hohneclrer,

Midland Park, NJ., assignors to Burroughs Corporation, Detroit, Mich., acorporation of Michigan Continuation of application Ser. No. 616,318,Oct. 16, 1956. This application Feb. 17, 1960, Ser. No. 9,392. Claims.(Cl. 34h-174.1)

This invention relates to a storage or memory system for use with a dataprocessing system. More particularly, the invention relates to ahigh-speed magnetic-disk memory. This application is a continuation ofapplication Vfor U.S. patent Serial No. 616,318, led October 16, 1956now abandoned, bearing the names of George G. Hoberg and Otto 'Hohneckenentitled Magnetic Storage System.

lA principal object of the invention is to provide, for use with a dataprocessing system, an external memory of large capacity and in a formreadily and directly usable by the data processing apparatus Without theinterposition of converters or speed-matching butter circuits.

As is Well known, data processing systems frequently require a largecapacity external memory in the form of. a record which may be storedaway until needed. In some systems, the external memory is in the formof punched cards; in others, punched tape; in still others, magnetictape. These forms of external memory are not adapted to high speedoperation and necessitate the use of converters and speed-matchingbuffer stages to put the stored data into a form which is usable at thehigh speeds required by the data processing circuits.

According to the present invention, a large external memory is providedcomposed of magnetic-surfaced disks which may be placed on a turntableand driven rotationally at high speed, the disks being readily removablefor storage and to make the turntable available to other disks. Thespeed at which the turntable is driven is suiiiciently high to .permitthe data delivered by the data processing circuits -to be recordeddirectly on the magnetic disks, and the data read from the disks to beused directly by the data processing circuits, in each case Without theinterposition of a buier memory. It will be readily understod that ifthe speed of the turntable were slow, for example, of the 'order of thatused in phonographs, it would be necessary to provide magnetic shiftregisters or other forms of buer memory to match the then slow recordingand reading speeds with the high speeds required by the data processingcircuits. The need for buffer memory stages is avoided, in the systemofthe present invention, by the use of a high speed turntable and by meanswhich permit the high speed turntable to be used.

The present invention contemplates that a-method of magnetic recordingknown as selective alteration will or may be used. This method ofrecording has certain known advantages and is widely used. In selectivealteration, at least asthe term is used in this spccication, eachelemental area or cell of the magnetic-record surface is capable ofrepresenting a unit'of information indicated by au appropriate level ofor change-in surface'magnetization, which unit of information willhereinafter be referred to as a bit, and each bit of a prior recordingis adapted selectively to be altered, or to remain unaltered, by a laterrecording. YStated another Way, in selective alteration a priorrecording is not erased before entering a cceeding recording. Rather,the earlier recording is obliterated by the'later, since each bit of thelater data is Written right over the corresponding bitsof the Apreviousdata, thepolarity of some of the cells being changed by the new writing,the polarity of other cells Iremaining unchanged, accordingto therelationship between the old and new information. It will be seen that,in the selective al- 3,090,947 Patented May 21, 1953 ice -terationmethod of magnetic recording, itis important that each succeeding bit beapplied to the magnetic surface'at precisely the location of theelemental area or cell occupied by the previous bit. If `the recordinghead is not accurately located with respect to the track, or, if theinstant of recording does not correspond exactly with that or thepreviously recorded data, the later recording will not be in preciseregistration With the earlier, and the prior bits of data will not becompletely altered by the later. Thus, remnants of bits will remain toclutter up the recording and to jeopardize the accuracy of thesubsequent readings.

In the system of the present invention, where the external memory iscomposed of a large number of magnetic disks each `of which is intendedto be lremoved Ifrom the turntable on which the recording takes place,stored away, and later brought forth and placed `again on the sameturntable for reading of the recordeddata and the recording of new data,if a selective alteration form of recording is :to be employed, tworequirements must be met; one, that each disk be replaced on the4turnable in precisely the same position previously occupied, vboth asto center location and as to angular orientation, and two, that the timeinstants of :the succeeding recording be exactly in phase with those ofthe earlier recording.

The present invention provides means for meeting both of the aboverequirements. In one embodiment, the means for `achieving the iirstrequirement is a pair of notches which are provided in each magneticdisk and which cooperate with positioning means located on the surfaceof the turntable, .the lattermeans, in one embodiment, .taking the formof guide posts, thrust means and clamping fingers. The secondrequirement is met by using timing signals which have a xed timerelation to the bits recorded on the magnetic disks. This isaccomplished by inscribing the timing .signals on the surface of theturntable. It will be appreciated -thatif the :timing signals were to beobtained from a fixed source suchV that the time spacing between timingsignals were equal and invariable, then the slight variations whichnnavoidably occur in the speed of the turntable due, for example, toline voltage variations, would tend to prevent a succeeding recordingfrom occupying precisely the same cell locations as a prior recording.This is avoided, `in accordance with the present invention, by usingtiming` signals which are inscribed on .the turntable itself, since anyvariations in turntable speed aiiect in like manner the time spacingbetween timing signals and cell locations.

Accordingly, another object of the present Yinvention may be said `to bethe provision of means, in an external memory system composed ofremovable magnetic ,disks and in which a selective alteration method ofrecording is used, for enabling a succeeding recording on `a disk to bein precise registration with a prior recording on that disk.

Since the system of the present application is capable of use whereselective alteration of pulse-type digital data is required, it can alsobe used where the disk recording involves other forms of datarepresentation, such as .analogue representation of quantities, whichmight require `similar precision in registration between the data andsuch reference positions and signals as are provided by the diskorienting means and the timing tracks.

It should be mentioned here that the present invention contemplates thatthe timing signals which are inscribed on the turntable will or may bethe only timing signals available to and used in the data processingsystem, these timing signals being employed either directly or inconjunction with other circuits such as iiip ilops to generate controlor gate pulses to control accurately the timing of the variousoperations performed throughout the data processing system.

l cathode ray storage tube.

invention, it is apparent that the internal memory must be be elsewherethan on the removable magnetic disks Since the information of the diskis not always accessible to Vthe data processingl apparatus. Accordingto the present invention the internal memory is recorded on theturntable itself where it s always accessible.

In order that the overall operating speed of the data processing systemmay =not be unduly impaired, it 1s desirable, of course, that thereplacement on the yturntable of one magnetic disk with another beaccomplished in a minimum amount of time. Accordingly, dynamic brakingand indexing means are provided to quickly bring the high speedturntable -to a stop in a preselected indexed position which is sorelated to the turntable-mounted diskdisks.

A further object of the present invention may, therefore, be said to bethe provision of means, in a data processing system employing removablemagnetic disks las an external memory, for enabling the magnetic disksto be changed in a minimum amount of time.

Data processing systems also usually include control pulses to directthe sequence of operations, to interpret coded instructions, and toinitiate the signals to the various processing circuits to execute theinstructions. In the system of the present application, such controlpulses are recorded on the turntable.

Data processing systems also ordinarily include program instructions. Inthe system of the present application, the program instructions may berecorded in part on For example, program-modification instructions maybe recorded on selected disks and used to alter the program krecorded onthe turntable; Or sub-routine program instructions may be recorded onthe disks and used in combination with a principal program recorded onthe turny table.

Data processing systems also frequently include socalledrevolver orrecirculating memory tracks.- In .the system of the present application,such .revolver or recirculating memory tracks may be included either onthe turntable or on the magnetic disks, or on both.

could alsobe inscribed on each disk, as well as on the turntable. Suchtiming signals on the disks may either be pre-inscribed or may bewritten thereon using Vthe timing signals on the turntable as thesource. Itis, however, not advantageous to place timing signals also onthe disks, and the present invention is intended to make the sameunnecessary. To have timing signals on each disk would not only use updisk surface and require additional reading heads, but would necessitatethe use of additional circuit and switching means since the timing onthe disk would not necessarily be phased with that on the turntable.Thus, l'a revolver type of accumulator could not be used, at least notdirectly, and a static type of register would be required. Moreover, theproblem'of accurately positioning the removable disks on the turntablewould not be Vcompletely avoided; it would still be necessary to accu-In the system of the present Apositioning means as to facilitate `suchrapid change of I y lthe turntable and in part on the replaceablemagnetic disks. A

4 rately locate the center of the disk so that the heads would be inregistry with the tracks.

The present invention contemplates, therefore, that timing signals willnot be inscribed on each individual disk, and that a single source oftiming signals will be provided, namely, markers pre-inscribed on theturntable. While other means of using these turntable-inscribed markersignals could be used,such for example, zasderiving error signals toindicate the timing relationships between the turntable timing markersand the bit readings from the disks and using such error signals incombination with delay circuits, buifer stages and -other electronicmeans to compensate for any time differences, the present inventionemploys mechanical means for .locating the removable disks on theturntable with su'icient accuracy, both las to location of center andangular orientation, to

' assure that the data are recorded on and read from the disks inprecise registration with respect to the discrete elemental areas orcells of magnetic information.

While the foregoing is a summary, the invention will be best understoodfrom a consideration of the following detailed description of oneembodiment taken together with the drawing wherein:

FIG. l is a diagrammatic illustration of a computer system employing thepresent invention;

FIG. 2 is a top view of the turntable yshowing diagrammatically themeans employed to obtain accurate positioning of the disk on theturntable;

FIG. 3 is a diagram of the circuit of the turntable motor employed toeffect braking and indexing; and

FIG. 4 is a cross-section along the line lZL-4 of FIG. 2.

Referring now to FIG. l, there is showmpartly in block diagram form, adigital computer system comprising a data processing system 10 to whichinput data may be applied from an external source r.l2 which may, forexample, be a machine for handling punched tape. Also applied to thedata processing system 10 by way of lead 21 are informational datapicked up Vfrom the replaceable magnetic disks which constitute theexternal memory, one of which, disk 34, is shown in FIG. 1. As shown,the data recorded on the magnetic disk 34 is picked up by one of theheads 44;, 45, y46, these heads being representative of the considerablylarger number of heads used in an lactual machine. The particular headselected for reading at any given time is determined by the read circuitof block 19 under the control of the address selector 1S. The latter is,in turn, controlled by control circuit 16 under instructions from theprogram unit 14. The timing of the data y processing system 10 isapplied to an output unit 18 which may, for example, be a printer.V

In FIG. l, the output of the data processing system l0 is also shownapplied to a dip flop 20 and the outputs of flip ilop 20 are shownapplied to a pair of coincidence gates 22, 24 only one of which is openat a time, the other being closed, the condition of the gate beingdetermined by the state of the flip iiop 20. As shown arbitrarily inFIG. l, when ip flop 20 is in the 0 state, gate 22 is open and gate 24is closed, whereas when ip tiop 20 is in the l state, gate 24 is openand gate 22 is closed.

-In accordance with the presenceinvention, as has already been ndicated,timing pulses are inscribed or Yrecorded on one or more tracks on theundersurface 32 of the yturntable 30. In FIG. 1, marker or di-git timingpulses are assumed to be magnetically recorded on a track read by head23, and -word timing pulses are assumed to be recorded on a track readby head 29. .Other timing pulses, such as once-per-revolution pulses,may -be recorded on other tracks which, to avoid undue complexity,

control circuits 16 byV -state .of the ilip ilop 20. The gate outputpulses representing the digital numbers 1 or 0 are applied by Way of thewrite circuits of block 19 to one of the heads 44, 45, 46, theparticular head selected being determined by the address selector andthe selected head is effective to record the gate output pulses on themagnetizable surface of one ofthe removable disks, for example, the disk34. The gate output pulses may also be applied by way `of the Writecircuits of block i9 to one or more of the heads 26, 27, and by means ofthe selected head the pulses are recorded on the magnetizableunder-surface 32 of the turntable 3G. The datanrecorded by heads 26, A27may comprise the internal memory of the computer system. It will beunderstood, of course,that heads 26, 27 are merely representative-andthat the number of heads used will depend upon requirements. Whether theoutput pulses from gates 22, 24 are recorded only on the removable disk34, or only on the under-surface of the turntable 32, or on both, yandon which track or tracks, is determined, of course, by the writecircuits of block 19 under the control of the address selector 15 ascontrolled in turn by the control circuit 16 and the program circuitsd4.

Any of the group of turntable heads represented by 26, 27 may be used,if desired, for recording and reading of any control information whichit may be desired to record on the under-surface 32 of the turntable.This control information may reach the selected head or heads by way ofthe data processing system i0, Viiip op 20, gates 22, 24, and the Writecircuits of block 19.

The under-surface of the turntable may also include a `track employed asa revolver or recirculating memory, as

is indicated in FIG. l by the read head `13, the write head and therevolver accumulator 17. It will be understood that the read and Writeheads 13, 25, operate on the same track.

Insummary, FIG. 1 illustrates a turntable 3G on the magnetizableunder-surface 32 of lwhich timing pulses and an internal memory arerecorded, together, if desired, with Ya recirculating memory, control,and program information, and in which the informational data of theexternal memory are recorded on removable disks represented in FIG. 1 bydisk l34.v It is'the infomation on the turntable which ties togetherland coordinates the data on the various removable records.

Assume now that disk 34, having been removed from the turntable andplaced in a storage cabinet -for some time, lhas now been returned tothe turntable Where it is required to occupy, Within very closetolerances, the same location of center and the same angular`orientation rela- Itive to the turntable, that previously obtained.Assume that such accurate placement of disk 34 has been accomplished,the means for such accomplishment being described more fullyhereinafter. The data previously recorded on disk 34 may now be pickedup, as by head 44 functioning as a read head, and -applied by way of thereadcircuits of block 19 to the data processing system l@ by Way of lead21. lThe passage of the data pulses through circuit 19 is controlled bytiming pulses picked up from the underside of the turntable by read head23 and delayed a proper amount by means 5? to compensate for theV factthat the recording process may require yclocking of read-back signals ata tLne in the basic timing-pulse cycle which may be different from thetime at which a writing pulse occurs.

As already indicated hereinbefore, for the system now being described tofunction properly, it is important that the disk be yaccurately replacedon the turntable in the same location and same orientation whichpreviously existed during the recordingV of the data thereon. While themeans by which this is accomplished is shown diagrammatically-in FIG. 2,the detailed structure is shown,

"5 described -and claimed in co-pending application of Otto Hohnecker,filed May 29, 1956, Serial No. 587,989, now Patent No. 2,937,916 andassigned to the assignee of the present application.

Referring now to FIG. 2, which is a diagrammatic View looking down ontheturntable 30, the disk S4-is shown as having a circular peripherysubstantially coincident with that of the turntable except for theL-shaped notched portions 51, 52 designed to cooperate with stop members53, 54 xed to the upper-face of the turntable atopposite sides thereof.As shown in FIG. 2, and also in FIG. 4 which is a cross-section takenalong the line 4-4 of FIG. 2, stop members 53, 54 have straight-edgebottom portions S5, 56, preferably located on the transverse diam- Veterofthe turntable which function as stops for the Itransversestraight-edgelower portions of notches 51, 52 of the disk 34. Each Vofthe stop members 53, 54 has a raised portion 68, 69 having an arcuateinner face'57 generated on a radius preferably having the same center asthe turntable. The inner portion of each stop member is so dimensionedas lto permit the upper portion of disk 34 to slide into place betweenthem, the arcuate faces 57 serving to deflect a misplaced entering diskinto its proper position between the stops.

To assist in the rapid manual placement of a disk on the surface of theturntable in a proper position -to be guided by stop members 53, 54 intoits finaland accurately positioned location, L-shaped shelf members 58,59 are provided. The surfaces 58a, 59a of the shelf members are eitherin the same plane as or slightly above the surface of the turntable, asshownby `58a in FIG. l, so that a record may be placed on the shelf andslid forward in the direction of the dotted arrow (FIG. 2) Von to theturntable. Guard members 72, 73 overhang the shelf surfaces and preventthe disk, .as it is slid on to the turntable, from being raised at an,angle sufficient to cause the disk to contact the disk recordingreadingheads, such as 3l, 33, 44, 45 and 46 (FIG. l). These heads, as well asothers not shown, are supported by known and suitable means above theturntable.

It will be seen from the Yabove that a disk such as disk 34, can be slidacrossthe face of the turntable, between the turntable surface andtheoverhanging recording or -reading headsuntil the transversestraight-edgedportions of the disk notches 51, 52 seat against thebottom edges 55, 56 ofthe stop members 53, 54.

During the time that disks 'are being removed from and placed on v`theturntable, a retractable latch assembly 60, located in a Well at thecenter of the turntable, is retracted belovvtheV turntable surface, `asby depressing bushing 61. The function of retractable latch assembly 64)is to accurately position and positively lock disk 34 in place upon theturntable. .The assembly 6i) includes three retractable latch ngers 62which lie below the plane of the upper sur-facelof the turn-table whenthe latch assembly is'in retracted position so that the disk can be slidfreely along the surface without striking the fingers. When actuated tolocking position, as Vby depressing push-button64, the fingers 62 swingupwardly through the hole to overlie the disk. The latch assemblycarries a pus-her member having anarcuate face, the radius of which hasthe same axis as the turntable center hole. The pusher-member 65 engagesthe rim of the hole of the diskand thrusts the disk angularly in thedirection indicated'by the arrow'66, which may, for example, be 30 oithe normal. This angular thrust forces both the transverse and verticaledges of the left disk-notch into firm contact with the transverse landvertical edges 55, 67, respectively, ofthe left Vstop member, andralsoforces the transverse edge of theright disk-notch into firm contact withbottom edge 56 of the right stop member. In this manner, positioning ofa disk Within close tolerances is accomplished. -As is shown clearly inFIG. 4, there is ordinarily no rm contact between the vertical edge -74of the-right disk-notch and the vertical edge of the right stopmember.54, the same not space available along this edge facilitatingplacement of the disk on the turntable without encountering binding.

.As previously indicated,.the structures of the retractablelatch'assembly 60 and of the stop members 53, 54 are shown and describedin detail, and claimed, in the aforementioned copending application ofOtto Hohnecker, one of the joint inventors of the invention describedand claimed inthe present application.

Attention now is called to the -fact that during operation turntable 30is driven yat high speed, for example 3600 r.p.m., by motor 40 (FIG. l)and that when `a disk j is to be changed considerable time could be lostif it were necessary to wait for turntable 34 to come to rest aftermotor 40 is shut off. To reduce the time required for record changing,motor 40 is designed and built to provide A three functions; rst, toaccelerate rapidly to, and thereafter to drive the turntable at, aconstant speed; second, to dynamically brake the turntable in responseto a control switch; and third, to bring the turntable to a stop in apreselected indexed position, indicated in FIG. 2 by the solid arrow 70.It 'will be seen that in this position, the stop members of theturntable are in optimum position to permit the removal of the in-placerecord and to receive Y the replacement record.

The manner in which motor 40 functions can be most readily explained byconsidering the circuit of motor 40 yshown in FIG. 3. As there shown,motor 40 is a single Y phase induction motor having a main statorwinding 85 and also an `auxiliary stator winding 86 which together withcondenser 89 provides the necessary magnetic-held asymmetry to get themotor started. The rotor windings, represented by 87, provide thepositioning feature, as will be described. The -m'otor assembly includesa step-down transformer 88 which steps the line voltage (230 volts) downto 40 volts. The assembly also includes a full-wave rectier 90comprising four selenium rectifiers.

To start the motor, the switches to points 91 and 93 are Yclosed and theswitches to points 92 Yand 94 are open.

This places full line voltages across the main and auxiliary windings ofthe stator and the motor rapidly accelerates to rated speed, 3600 r.p.m.During acceleration and running at rated speed, the rotor windings 87are shorted by the closed switch at point 93, and also by a centrifugalswitch 95 which is closed centrifugally against the action of a bias,indicated in FIG. 3 by the spring 96.

YTo stop the motor, the switches to points 91 and 93 are opened and theswitches to points 92 and 94 are closed. When this is done, the linevoltage is removed from across the motor stator and is placed acrossstep-down transformer 88. The D.C. secondary voltage delivered byfull-wave rectifier 90 is applied 'across the stator winding 85 and aportion thereof, as determined by variable resistor 97, is appliedacross'the rotor windings 87. Direct current flows immediately throughstator winding 85 to effect dynamic braking of the motor. Rotor windingsS7 remain shorted, however, by closed centrifugal switch 95 until thespeed of the motor falls below a preselected low speed, for example, 400-r.p.m., at which time switch 95 opens and D.C. current from rectifier90 ows through the rotor windings 87. The eiect of having direct currentowing in the stator winding 85 and also in the rotor windings 87 is tobring the rotor to a complete stop in a particular position indicated inFIG. 2 by the 'arrow 70 and hold the rotor in this position for theduration of this cycle or until the eurent is shut otf.V

No claim is made in this application to the positioning motor per se.This general type of motor is described, 'for example, in an article byC. S. Allen and H. Shapiro, entitled Rernote Rotational Positioning,published in Machine Design, April 1953, pages 243-247. Y

We have found that by using the particular embodiment of the inventiondescribed in'this'applicaftion, vthe high speed (3600 r.p.m.) turntablemay be brought to a 2,950,354, and assigned to the example, where aturntable is employed having a largerV diameter than that of the disks,the timing pulses may be recorded on yan area of the turntables uppersurfaceextending beyond the radius of the disks. Y

It should perhaps also be mentioned that in commercial practice thetiming tracks will, ordinarily at least, be inscribed on the turntablevat the factory rather than by the user of the computer. V

Also while the disks have been described in the present specication andshown in FIG. 2 as having a pair of L- shaped notches, otherconfigurations may be used to accomplish the -described result. Forexample, each disk may be substantially circular with ya pair of ears,located at opposite edges, cooperating with the turntables stop membersto effect accurate positioning and orientation of the disk.

It is also to be understood that while the disks are referred to in thespecification and also in the claims as magnetic disks, they maypreferably be comprised of -a non-magnetic material, such as aluminum,coated or plated with a magnetic material, such as iron oxide, or aferro-magnetic alloy or a ferrite. f Y

It is also pointed out that the disks may either warp slightly or forother reasons fail to be perfectly ilat, and that, as a consequence, thesurface of the rotating disk, at a particular lhead, will vary slightlyfrom a xed plane. Compensation for such variation may be furnished bythe use of movable air-floated heads, such as described and claimed inthe copending application of Otto Hohnecker, Serial No. 587,990, led May29, 1956, now Patent No. assignee of the present application. Y

What is claimed is: i

l. iIn a data storage system; a turntable having a plane magneticsurface on which timing signals are recorded; a disk removable withrespect to said turntable, said disk having at least one plane magneticsurface and having positioning notches in its periphery; guide meansleading to said turntable for sliding said disk onto the surface of saidturntable; stop means mounted on said turntable and adapted to cooperatewith the positioning notches in the periphery of said disk to controlits location and angular orientation; thrust means for urging said diskagainst said stop means; clamp means for clamping said disk on saidturntable, said thrust means and clamp means being retractable below theturntable surface during the slide-on portion of the disk-positioningoperation, said guide means, stop means, thrust means and clamp meansbeing cooperatively adapted to eiect positioning of Ysaid disk on saidturntable inA substantially the same precise position previouslyoccupied by said same disk with respect both to the center of the diskand to its angular orientation; means for rotating said turntable andthe clamped disk; means for dynamically braking and stopping saidturntable at an indexed position so related to said stop means and soaligned with said guide means as to facilitate rapid removal of saiddisk from, and placement of a succeeding disk on, said turntable;transducer means. for recording information on the plane magneticsurface of said disk and for reading therecorded information therefrom;and means for utilizing said turntable-recorded timing signals tocontrol the timing of said recording by said transducer means. Y

2. iIn a data processing system; a turntable having a plane magneticunder surface on which data and timing signals are magneticallyrecorded; a disk having at least one plane magnetic surface, said diskhaving positioning means adapted to cooperate with means on saidturntable to position the disk with respect to itslocation andangular-orientation; guide means for confining said disk to ter thereof;stop means carried by said turntable for stopping said disk when itscenter coincides with the axis of said turntable; thrust means carriedby said turntable for urging said disk against said stop means forpositioning said disk on said turntable in substantially precisely thesame position previously occupied by said same disk with respect both tothe center of said disk and its angular orientation; clamp means carriedby said turntable for clamping said disk in said position, said thrustmeans and clamp means being adapted to be retracted below the turntablesurface during the slide-on portion of the diskpositioning operation;means for rotating said turntable and clamp disk together; means forstopping said turntable in an indexed position, said indexed positionbeing related to said stop means and to said guide means as tofacilitaterapid removal of a disk from, and placement of a succeedingdisk on, said turntable; means for magnetically recording bits ofdataon, and reading said bits of recorded data from, said disk clampedon and rotating with said turntable; and means for utilizing the timingsignals recordedon the under surface of said turntable for controllingthe times of said recording.

3. In a data storage system;a turntable having a plane magnetic surfaceon which timing signals are recorded; a disk removable with respect tosaid Vturntable and having at least one plane magnetic surface;positioning means on said turntable; means on said disk adapted tocooperate with said positioning means on said turntable for securingsaid disk on said turntable in substantially precisely vthe sameposition previously occupied by said same disk with respect both to lthecenter of the disk and to its angular orientation; means rfor rotatingsaid turntable and said secured disk together about a common axis; meansfor stopping said turntable at an indexed position so related to saiddisk-securing means as to facilitate rapid replacement of said disk Withanother; transducer means for magnetically recording bits of informationon, and reading said recorded bits of information from said disk; andmeans for utilizing said turntable-recorded timing signals to controlthe times of said recording.

4. In a data processing system; a turntable having a plane magneticsurface on which signals are magnetically recorded; -positioning meanson said turntable; a disk having at least one plane ,magnetic surface,said disk being removable with respect to said turntable, said diskhaving means adapted to cooperate with said positioning means on saidturntable to identify the angular orientation of said disk with respectto said-turntable; clamp means for clamping said disk physically onsaidturntable in substantially precisely the saine position previouslyoccupied bysaid disk with respect both to the centerV of said disk andits angular orientation; means for rotating said turntable and saidclamped disk together about their common axis; means for magneticallyrecording information on, and reading information from, the planemagnetic surface of saiddisk; and `means for utilizing saidturntable-recorded signals to control the times of said recording.

5. In a data memory system; a turntable rotatable about a xed axis andhaving a -magnetic surface on which timing signals are recorded;positioning means on said turntableadiskhavingat least one planemagnetic surface, 'said disk -being Vremovable from said turntable,said'disk having-positioning means adapted to cooperate withsaidpositioning'means on'said turntable to enable repeated placementl ofsaid disk on said-turntable in substantially the same precise positionpreviously occupied by said disk With respect both to the center of thedisk and its angular orientation; means for physically securing saidturntable and said disk together in said position for joint rotation;means for rotating said turntable and said diskA together about said xedaxis; transducer means for magnetically recording digital informationon, and reading the recorded information from, said disk; and means forutilizing the ,timing signals recorded on said turntable surface tocontrol the times of said recording.

6. A turntable assembly comprising, in combination', a turntablehaving avportion on which timing signals are recorded, positioning means on theupper sur-face of the turntable arranged to receive a -magneticrecordingdisk,

said positioning means comprising a pair of stop members located onopposite sides of fthe upper surface of the --turntable and havingforward straight-edges located on substantially the transverse diameterof the turntable 'and having side edges generally converging toward oneanother, said stop members presenting an entrance therebetween forreceiving a portion ,of a'disk positioned on the turntable, a stationarydisk sliding guide positioned alongside of and on substantiallyl thelevel of the upper surface of the turntable, means for rotating saidturntable, means for dynamically braking and'stopping said turntablewith the entrance formed by the stop mem-bers in line with the disksliding guide, lmeans juxtaposed to said turntable for sensing -saidtiming signals as the turntable is rotated, ,and transducer means sopositioned .'with respect -to the turntable las to sense the magneticrecordin'g on a disk positioned thereon, and means connected to saidtiming signal sensing means for utilizing said turntable-recorded timingsignals to control the operation of said transducer means.

7. Inadata storage system; a turntable; a disk removable With respect tosaid turntable, said disk having at least ,one plane magnetic surfaceand having positioning notches in its periphery; guide means leading tosaid turntable for sliding said fdisk onto lthe surface of saidturntable; `stop means mounted on said turntable and adapted tocooperate With the positioning notches in the periphery of said disk tocontrol its location and angular orientation; thrust means for urgingsaid disk against said stop means; clamp means for clamping said disk onsaid turntable, said thrust means andclamp'means being re- Y-tractablebelow the turntable surface during the slide-on Y on said turntable -insubstantially the same precise position previously occupied by said samedisk with respect iboth to the center of the'disk and to its :angularorientation; means for rotating said turntable and the clamped disk;means for dynamicallybraking and stopping said turntable at `an indexedposition so related to said stop means and so aligned with said guidemeans las to facilitate rapid removal of said disk from, and placementof a succeeding disk on, said turntable, and transducer means forrecording information on the plane magnetic sur-face of said disk andfor reading the recorded information therefrom.

8. -ln a data processing system; a turntable, a disk having at least oneplane vmagnetic surface, said disk having positioning lmeans adapted tocooperate vwith means on said'turntable to position ythe disk withrespect to its location and angular-orientation; guide means forconfining said disk to a slide-on path of travel the centerline of whichleads over the .upper plane surface of said turntable to the centerthereof; stop means carried by said turntable for stopping said diskwhen its center coincides Awith the axis of said turntable; thrust meanscarried by said turntable for urging said diskagainst said stop meansfor positioning said disk on said turntable in substantially preciselythe same position previously occupied by Vsaid samediskwith respectbothto the center of said portion of the disk-positioning operation;means for rotating said turntable land clamped disk together; means forstopping said turntable in an indexed position, said indexed positionbeing related to saidstop means and to said guide means :as tofacilitate rapid removal of a disk `troni, an'd placement of asucceeding disk on, said turntable; and means for magnetically recordingbits of data on, and reading said bits of recorded data from, said diskclamped on and rotating with said turntable.

9. In #a data storage system; a turntable, a disk removable vvithrespect to said turntable and h-aving at least one plane magneticsurface -for continuous recording thereon during its lrotationalmovement on said turntable; positioning Vmeans on said turntable; meanson said disk adapted to cooperate with said positioning means on saidvturntable for securing said `disk on said turntable in substantiallyprecisely the same position previously occupied by said same disk Withrespect both to the center of fthe disk and to its angular orientation;means for unidirectionally rotating said turntable and said secured disktogether about a common axis; means for stopping said turntable -at asingle indexed position so related to said disk-securing means ias toIfacilitate rapid loading and subsequent replacement of said disk withanother; land transducer means for magnetically recording bits ofinformation on, reading said recorded bits of information Y:from saididisk; and means operatively related to said indexed position forcontrollin-g said transducer means.

10. In a data memory system; a turntable rotatable about la fixed axis,positioning means on said turntable;

'a-disk having at least one plane magnetic surfacefor about said fixedaxis; and means for dynamically braking fand stopping said turntablewith the positioning means thereon in a single position with respect toa `given side of the axis of rotation ofthe turntable to facilitateloading and unloading of said disk from said turntable.

.11. A turntable assembly comprising, in combination, a turntable,positioning means on the upper surface of the turntable arranged toreceive a magnetic recording disk, said positioning means 'comprising apair of stop members located on `opposite (sides of the upper surface ofthe turntable and having forward straight-edges located on substantiallythe transverse diameter of the turntable land havin-g side' edgesgenerally converging toward one another, said stop members presenting anentrance Itherebetween for receiving a portion of a disk positioned onthe turntable, a stationary disk sliding guide positioned 'alongside ofand on substantially the level of the upper surface of the turntable,means for rotating said t-urntable, 'means for dynamically braking andstopping said turntable with the entrance formed by the stop members inline with the disk sliding guide, and transducer means o associated withthe turntable iand positionable for sensing the magnetic recording on adisk carried by the turntable. Y Y

12. A data memory assembly comprising, in combination, a turntable,positioning means on the upper surface of the turntable arranged toreceive a magnetic recording Ymembers located on opposite sides ofV theupper surface ofthe turntable and having forward straight-edges locatedon substantially the transverse diameter of the turntable and presentingan entrance therebetween for receiving ra zportion of a disk positionedon the turntable, a stationary disk sliding guide positioned alongsideVof and on substantially the level of the uppersurface of the turntable,means for Vrotating said turntable, means for dynamically braking andstopping said turntable with the entrance formed by the pair of stopmembers in line with the disk sliding guide, and transducer meansassociated with the turntable and positionablerfor sensing the magneticrecording on a disk carried by the turntable.

13. A data memory 4assembly comprising, in combination, a turntable,positioning means on the upper surface of the turntable arranged toengage and properly seat Ya removable magnetic recording disk on theturntable, said Y positioning means comprising a pair of stop memberslocated on opposite sides of lthe upper surface of the turntable andpresenting an entrance therebetween for receiv- .ing a portion of :adisk positioned on the turntable, a

disk advancing guide positioned alongside of and on substantially lthelevel of the upper surface of the turntable, means for rotating saidturntable, means for dynamically braking and stopping said turntable'with the entrance 'formed bythe pair of stop members in line with Ithedisk advancing guide, and transducer means associated with the turntableand positionable for sensing the magnetic recording on la disk carriedby the turntable. 3()

Qtion, a turntable, disk position-ingmeans on' the upper Y14. A datamemory assemblycomprising, in combinasurface of the turntable arrangedto seat a recording disk Land enabling repeated placement of the disk onthe turn table in substantially the same precise position previouslyoccupied by the disk with respect both to the center of the disk and itsangular orientation, said positioning means providing an entrance forslide-on movement of a disk onto the upper surface of the turntable, adisk sliding guide positioned alongside of and on substantially thelevel of the upper surface of the turntable, means for rotating saidturntable, means for braking and stopping said turntable with theentrance of the positioning means in line with the disk sliding guide,and clamping means carried by the turntable for clamping such la disk insaid position, said clamping means being retractible below the uppersurface ofthe turntable during the slide-on movement of a disk.

15. A data memory assembly comprising, in combination, a turntable,positioning means on a surface of the turntable arranged to receive andseat a recording disk on the turntable for joint rotation therewith,said disk having a plane magnetic surface for continuous recorddisk,said positioning means comprising a pair of stop ing thereon during itsrotational movement on said turntable, said positioning means forming anentrance for receiving a portion of a disk positioned on the turntable,ia disk advancing guide at one side of an'd on substang tially the levelof .the upper surface Yof the turntable to facilitate loading andunloading of said disk, means for unidireotionally rotating saidturntable, and means for braking :and stopping said turntable with theentrance formed :by the positioning means in line with the diskadvancing guide.

VReferences Cited in the le of this patent UNITED STATES PATENTS2,722,676 Begun Nov. 1, 1955 2,739,299 Burkhan Mar. 20, 1956 2,846,661Cunningham Aug. 5, s 2,847,223 Taylor Aug. 12, 195s 2,937,916

Hohnecker May 24, 1960

1. IN A DATA STORAGE SYSTEM; A TURNTABLE HAVING A PLANE MAGNETIC SURFACEON WHICH TIMING SIGNALS ARE RECORDED; A DISK REMOVABLE WITH RESPECT TOSAID TURNTABLE, SAID DISK HAVING AT LEAST ONE PLANE MAGNETIC SURFACE ANDHAVING POSITIONING NOTCHES IN ITS PERIPHERY; GUIDE MEANS LEADING TO SAIDTURNTABLE FOR SLIDING SAID DISK ONTO THE SURFACE OF SAID TURNTABLE; STOPMEANS MOUNTED ON SAID TURNTABLE AND ADAPTED TO COOPERATE WITH THEPOSITIONING NOTCHES IN THE PERIPHERY OF SAID DISK TO CONTROL ITSLOCATION AND ANGULAR ORIENTATION; THRUST MEANS FOR URGING SAID DISKAGAINST SAID STOP MEANS; CLAMP MEANS FOR CLAMPING SAID DISK ON SAIDTURNTABLE, SAID THRUST MEANS AND CLAMP MEANS BEING RETRACTABLE BELOW THETURNTABLE SURFACE DURING THE SLIDE-ON PORTION OF THE DISK-POSITIONINGOPERATION, SAID GUIDE MEANS, STOP MEANS, THRUST MEANS AND CLAMP MEANSBEING COOPERATIVELY ADAPTED TO EFFECT POSITIONING OF SAID DISK ON SAIDTURNTABLE IN SUBSTANTIALLY THE SAME PRECISES POSITION PREVIOUSLYOCCUPIED BY SAID SAME DISK WITH RESPECT BOTH TO THE CENTER OF THE DISKAND TO ITS ANGULAR ORIENTATION; MEANS FOR ROTATING SAID TURNTABLE ANDTHE CLAMPED DISK; MEANS FOR DYNAMICALLY BRAKING AND STOPPING SAIDTURNTABLE AT AN INDEXED POSITION SO RELATED TO SAID STOP MEANS